Refrigerator and control method thereof

ABSTRACT

Disclosed are a refrigerator and a control method thereof. The refrigerator according to one aspect includes a main body having a storage chamber; a compressor configured to compress a refrigerant; a condenser configured to condense the refrigerant compressed by the compressor; an evaporation expander configured to depressurize the refrigerant condensed by the condenser; a first evaporator configured to evaporate the refrigerant depressurized by the evaporation expander and thus to cool the storage chamber; a condensing expander installed between the condenser and the evaporation expander and configured to depressurize the refrigerant condensed by the condenser; and a subsidiary condenser installed between the condensing expander and the evaporation expander and configured to condense the refrigerant depressurized by the condensing expander.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/325,813, filed on Jan. 12, 2017, which is U.S. National PhaseApplication under 35 U.S.C. § 371 of International ApplicationPCT/KR2015/007341, filed on Jul. 15, 2015, which claims the benefit ofKorean Application No. KR 10-2014-0092179, Korean Application No. KR10-2014-0092180, and Korean Application No. KR 10-2014-0092181, allfiled on July. 21, 2014, the entire contents of which are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to a refrigerator and a control methodthereof.

BACKGROUND ART

Generally, a refrigerator has a plurality of storage chambers foraccommodating stored things to keep food frozen or refrigerated, and onesurface of each of the storage chambers is formed to be opened for thefood to be received or taken out. The plurality of storage chambersinclude a freezing chamber for keeping the food frozen and arefrigerating chamber for keeping the food refrigerated.

In the refrigerator, a refrigeration system in which a refrigerant iscirculated is driven. The refrigeration system includes a compressor, acondenser, an expander and an evaporator. The evaporator may include afirst evaporator which is provided at one side of the refrigeratingchamber, and a second evaporator which is provided at one side of thefreezing chamber.

Recently, a refrigerator in which the evaporator and the expander areinstalled at the refrigerating chamber and the freezing chamber,respectively has been developed. In this refrigerator, an amount of therefrigerant supplied from the compressor to each evaporator is adjustedby controlling each expander, and each internal temperature of therefrigerating chamber and the freezing chamber are maintained at a coldtemperature and a freezing temperature.

Also, in consideration of target temperatures of the freezing chamberand the refrigerating chamber that are considerably different from eachother, a refrigerator in which a compressor for freezing and acompressor for refrigeration having different refrigeration capacitiesfrom each other are installed has been developed. In this refrigerator,each compressor is controlled based on the target temperatures of therefrigerating chamber and the freezing chamber, and thus each internaltemperature of the refrigerating chamber and the freezing chamber aremaintained at the target temperatures.

Here, the refrigeration capacity of the compressor for refrigeration isreduced to about 60% of that of a conventional compressor to increase anevaporation temperature of the refrigeration cycle for cooling therefrigerating chamber.

That is, the refrigeration further includes a small compressor having asmall refrigeration capacity to increase the evaporation temperature ofthe refrigeration cycle for cooling the refrigerating chamber.

However, in a conventional refrigeration system, a subsidiary condensermay be provided so that a plurality of condensing processes areperformed in the refrigeration cycle in some cases, but, in this case,there is a problem in that a radiant value of a main condenser islowered due to the subsidiary condenser, and thus cooling efficiency isreduced.

TECHNICAL PROBLEM The present disclosure is directed to providing arefrigerator in which an expander is additionally provided between acondenser and a subsidiary condenser to effectively cool a plurality ofstorage chambers.

Technical Solution

One aspect of the present disclosure provides a refrigerator including amain body having a storage chamber; a compressor configured to compressa refrigerant; a condenser configured to condense the refrigerantcompressed by the compressor; an evaporation expander configured todepressurize the refrigerant condensed by the condenser; a firstevaporator configured to evaporate the refrigerant depressurized by theevaporation expander and thus to cool the storage chamber; a condensingexpander installed between the condenser and the evaporation expanderand configured to depressurize the refrigerant condensed by thecondenser; and a subsidiary condenser installed between the condensingexpander and the evaporation expander and configured to condense therefrigerant depressurized by the condensing expander.

The refrigerator may further include a refrigerant pipe configured toguide a flow of the refrigerant condensed by the condenser; a firstbranch passage branched from the refrigerant pipe; a second branchpassage branched from the refrigerant pipe and in which the condensingexpander is installed; and a valve device installed at the refrigerantpipe and configured to branch the refrigerant to the first and secondbranch passages, and the evaporation expander, the first evaporator, thecondensing expander, and the subsidiary condenser are installed at thesecond branch passage.

A cold storage expander configured to depressurize the refrigerantcondensed by the condenser and a cold storage evaporator configured toevaporate the refrigerant depressurized by the cold storage expander maybe installed at the first branch passage.

The refrigerator may further include a cold storage part having a phasechange material (PCM) therein and in which the subsidiary condenser andthe cold storage evaporator are installed, and the cold storage part mayexchange heat with each of the subsidiary condenser and the cold storageevaporator.

The valve device may be a three-way valve having one inlet port andfirst and second outlet ports, and the first branch passage may beconnected with the first outlet port, and the second branch passage maybe connected with the second outlet port.

The refrigerator may further include an input part configured to receivean input of a desired temperature of the storage chamber, and atemperature sensor provided at an inside of the storage chamber, and,when a temperature detected by the temperature sensor satisfies thedesired temperature, the first outlet port is opened and the secondoutlet port is closed by the valve device and thus the refrigerant isguided to flow to the cold storage evaporator.

When the temperature detected by the temperature sensor does not satisfythe desired temperature, the second outlet port is opened and the firstoutlet port is closed by the valve device and thus the refrigerant isguided to flow to the first evaporator.

The refrigerator may further include a check valve installed at anentrance side of the first evaporator to guide a one-way flow of therefrigerant.

The storage chamber may include a refrigerating chamber and a freezingchamber, and the first evaporator may be installed at a rear wall of thefreezing chamber, and the cold storage evaporator and the subsidiarycondenser may be installed at a rear wall of the refrigerating chamber.

The refrigerator may further include a second evaporator installed at anexit side of the cold storage evaporator to evaporate again therefrigerant evaporated by the cold storage evaporator.

Another aspect of the present disclosure provides a refrigeratorincluding a first refrigeration system including a first compressor, afirst condenser, a first evaporation expander, and a first evaporator;and a second refrigeration system including a second compressor, asecond condenser, a second evaporation expander and a second evaporatorand configured to exchange heat with the first refrigeration system,wherein the second refrigeration system include a condensing expanderconfigured to depressurize a refrigerant condensed by the secondcondenser, and a subsidiary condenser installed between the secondevaporation expander and the condensing expander and configured tofurther condense the refrigerant depressurized by the condensingexpander.

The refrigerator may further include a subsidiary evaporator configuredto evaporate the refrigerant depressurized by the first evaporationexpander.

Still another aspect of the present disclosure provides a method ofcontrolling a refrigerator which includes a compressor, a condenser, anevaporator configured to cool a storage chamber, an evaporation expanderprovided at an entrance side of the evaporator to depressurize arefrigerant, and a cold storage evaporator configured to store cold airin a cold storage part, including driving the compressor, andintroducing the refrigerant passing through the condenser into at leastone of the evaporator and the cold storage evaporator by a valve device;and determining whether a temperature of the storage chamber satisfies adesired temperature, wherein, when the temperature of the storagechamber does not satisfy the desired temperature, the refrigerant flowsthrough a condensing expander provided at an entrance side of theevaporator and a subsidiary condenser, and is introduced into theevaporator.

When the temperature of the storage chamber satisfies the desiredtemperature, the refrigerant flows through a cold storage expanderprovided at an entrance side of the cold storage evaporator and asubsidiary condenser, and is introduced into the cold storageevaporator.

Advantageous Effects

According to the embodiment proposed in the present disclosure, theradiant value of the condenser can be prevented from being lowered dueto the subsidiary condenser, and thus the cooling efficiency of therefrigeration cycle can be increased.

Also, since the phase change material (PCM) is used as the cold storagematerial, the heat exchanging efficiency of the heat exchanger can beenhanced, and the internal temperature of the refrigerator can beconstantly maintained.

Also, since a separate device for increasing the cooling efficiency,except the additional expander, is not provided, an internal design ofthe refrigerator is simple, and the space of the storage chamber can beeffectively used.

Also, since the present disclosure has a simple cycle structure, themanufacturing cost thereof can be reduced.

DESCRIPTION OF DRAWINGS

Embodiments will be described in detail with reference to the followingdrawings in which like reference numerals refer to like elements, andwherein:

FIG. 1 is a view illustrating an internal structure of a refrigeratoraccording to an embodiment of the present disclosure;

FIG. 2 is a system view illustrating a refrigeration cycle structure ofthe refrigerator according to the embodiment of the present disclosure;

FIG. 3 is a view illustrating a partial structure of the refrigeratoraccording to the embodiment of the present disclosure;

FIG. 4 is a cross-sectional view taken along a line I-I′ of FIG. 1;

FIG. 5 is a control block diagram of the refrigerator according to theembodiment of the present disclosure;

FIG. 6 is a flowchart illustrating a method of controlling therefrigerator according to the embodiment of the present disclosure;

FIG. 7 is a graph illustrating a P-H diagram of a refrigerant circulatedin the refrigerator according to the embodiment of the presentdisclosure;

FIG. 8 is a system view illustrating a refrigeration cycle structure ofa refrigerator according to another embodiment of the presentdisclosure;

FIG. 9 is a view illustrating a partial structure of the refrigeratoraccording to another embodiment of the present disclosure;

FIG. 10 is a longitudinal cross-sectional view of the refrigeratoraccording to another embodiment of the present disclosure;

FIG. 11 is a control block diagram of the refrigerator according toanother embodiment of the present disclosure;

FIGS. 12 and 13 are flowcharts illustrating a method of controlling therefrigerator according to anoter embodiment of the present disclosure;

FIG. 14 is a graph illustrating a P-H diagram of a refrigerantcirculated in the refrigerator according to another embodiment of thepresent disclosure;

FIG. 15 is a view illustrating an internal structure of a refrigeratoraccording to still another embodiment of the present disclosure;

FIG. 16 is a transverse cross-sectional view taken along a line I-I′ ofFIG. 15;

FIG. 17 is a longitudinal cross-sectional view taken along a line II-IIof FIG. 15;

FIG. 18 is a view illustrating a refrigeration cycle structure of therefrigerator according to still another embodiment of the presentdisclosure;

FIG. 19 is a graph illustrating a P-H diagram of a refrigerantcirculated in the refrigerator according to still another embodiment ofthe present disclosure;

FIG. 20 is a control block diagram of the refrigerator according tostill another embodiment of the present disclosure; and

FIG. 21 is a flowchart illustrating a method of controlling therefrigerator according to still another embodiment of the presentdisclosure.

MODE FOR INVENTION

Hereinafter, embodiments will be described in detail with reference tothe accompanying drawings. The embodiments may, however, be embodied inmany different forms and should not be construed as being limited to theembodiments set forth herein; rather, alternate embodiments fallingwithin the spirit and scope will fully convey the concept to thoseskilled in the art.

FIG. 1 is a view illustrating an internal structure of a refrigeratoraccording to an embodiment of the present disclosure.

Referring to FIG. 1, the refrigerator 1 according to the embodiment ofthe present disclosure includes a main body 11 of which a front surfaceis opened, and a storage chamber which is formed at an inside of themain body 11.

The storage chamber includes a refrigerating chamber 12 and a freezingchamber 13. The refrigerating chamber 12 and the freezing chamber 13 maybe divided by a division part 14. The refrigerating chamber 12 and thefreezing chamber 13 may be referred to as a “first storage chamber” anda “second storage chamber,” respectively.

The refrigerator 1 may include an outer case 15 which forms an exteriorthereof, a refrigerating chamber inner case 16, and a freezing chamberinner case (not shown).

The refrigerating chamber inner case 16 is disposed at an inside of theouter case 15 to form an inner surface of the refrigerating chamber 12.Also, the freezing chamber inner case (not shown) is disposed at theinside of the outer case 15 to form an inner surface of the freezingchamber 13.

The refrigerator 1 may further include a freezing chamber door 21 and arefrigerating chamber door 22 which are coupled to a front side of themain body 11 to selectively open and close the freezing chamber 13 andthe refrigerating chamber 12.

In the embodiment, a bottom freezer type in which the freezing chamberis formed at a lower portion thereof and the refrigerating chamber isformed at an upper portion thereof will be described as an example.However, the spirit of the present disclosure may be applied to not onlythe above-described structure of the refrigerator, but also a top mounttype in which the freezing chamber is formed at an upper portion thereofand the refrigerating chamber is formed at a lower portion thereof, or aside-by-side type in which the freezing chamber and the refrigeratingchamber are provided at left and right sides thereof.

The refrigerator 1 may further include a refrigerating chamber coverplate 23 provided at the refrigerating chamber 12. The refrigeratingchamber cover plate 23 may be provided at a rear surface of therefrigerating chamber 12.

A cold air discharging part 18 through which cold air is discharged tothe refrigerating chamber 12 may be provided at the refrigeratingchamber cover plate 23.

A refrigerating chamber cover plate (not shown) having cold airdischarging part (not shown) through which cold air is discharged may bealso provided at a rear surface of the freezing chamber 13.

FIG. 2 is a system view illustrating a refrigeration cycle structure ofthe refrigerator according to the embodiment of the present disclosure.

Referring to FIG. 2, the refrigerator 1 according to the embodiment ofthe present disclosure includes a first refrigeration system 10 and asecond refrigeration system 20. Each of the first and secondrefrigeration systems 10 and 20 includes a plurality of devices fordriving a refrigeration cycle.

The first refrigeration system 10 includes a first compressor 110 whichcompresses a first refrigerant flowing in the first refrigeration system10 and discharges the first refrigerant in a high temperature and highpressure state, a first condenser 120 which condenses the firstrefrigerant compressed by the first compressor 110 and maintained in thehigh temperature and high pressure state through radiation of heat, afirst expander 141 which receives and depressurizes the refrigerantcondensed by the first condenser 120, a subsidiary evaporator 153 whichevaporates the refrigerant depressurized by the first expander 141, anda first evaporator 150 which evaporates the first refrigerant flowing inthe subsidiary evaporator 153. The first expander 141 may be referred toas a “first evaporation expander.”

The first refrigeration system 10 includes a refrigerant pipe 100 whichconnect the first compressor 110, the first condenser 120, the firstexpander 141, the subsidiary evaporator 153, and the first evaporator150 to guide a flow of the refrigerant.

The second refrigeration system 20 includes a second compressor 210which compresses a second refrigerant flowing in the secondrefrigeration system 20 and discharges the second refrigerant in a hightemperature and high pressure state, a second condenser 220 whichcondenses the second refrigerant compressed by the second compressor 210and maintained in the high temperature and high pressure state throughradiation of heat, a second expander 143 which receives anddepressurizes the refrigerant condensed by the second condenser 220, asubsidiary condenser 223 which condenses once more the secondrefrigerant depressurized by the second expander 143, a third expander145 which depressurizes the second refrigerant condensed by thesubsidiary condenser 223, and a second evaporator 250 which evaporatesthe second refrigerant depressurized by the third expander 145. Thesecond expander 143 performs depressurizing for subsidiary condensing,and thus may be referred to as a “condensation expander,” and the thirdexpander 145 may be referred to as a “second evaporation expander.”

In the subsidiary condenser 223, the refrigerant is condensed at a lowerpressure than that in the second condenser 220. The second expander 143may prevent a radiant value of the condenser 120 from being reduced dueto the subsidiary condenser 121.

The subsidiary condenser 223 may be installed adjacent to the subsidiaryevaporator 153 so as to exchange heat with the subsidiary evaporator153. Specifically, the second refrigerant flowing through the subsidiarycondenser 223 may be condensed using the cold air generated when thesubsidiary evaporator 153 evaporates the first refrigerant. Thesubsidiary condenser 223 and the subsidiary evaporator 153 may be incontact with each other, but heat may be exchanged using a heat exchangeplate 190 which will be described later.

When the refrigerant condensed by the second condenser 220 isdepressurized by the second expander 143, and then introduced into andcondensed once more by the subsidiary condenser 223, cooling performancemay be enhanced. Enhancement of the cooling efficiency will be describedlater in detail with reference to FIG. 7.

The first to third expanders 141, 143, and 145 may be commonly referredto as an expander 140, and may be opened and closed according to adriving signal of a control part.

Specifically, when a refrigeration temperature of the refrigeratingchamber 12 is higher than a first target temperature, the first expander141 may be opened so that the first refrigerant is supplied to the firstevaporator 150, and when the refrigeration temperature of therefrigerating chamber 12 arrives at the first target temperature, thefirst expander 141 may be closed so that the first refrigerant suppliedto the first evaporator 150 is blocked.

When a freezing temperature of the freezing chamber 13 is higher than asecond target temperature, the second and third expanders 143 and 145may be opened so that the second refrigerant is supplied to the secondevaporator 250, and when the freezing temperature of the freezingchamber 13 arrives at the second target temperature, the second andthird expanders 143 and 145 may be closed so that the refrigerantsupplied to the second evaporator 250 is blocked. Even when one of thesecond and third expanders 143 and 145 is closed, the refrigerantsupplied to the second evaporator 250 may be blocked.

That is, the refrigerant is supplied to the first and second evaporators150 and 250 according to opening driving of each of the first to thirdexpanders 141, 143 and 145. The first to third expanders 141, 143, and145 may include capillary tubes.

When the first expander 141 is opened and thus the first refrigerant issupplied, the first evaporator 150 serves to cool surrounding air andair in the refrigerating chamber 12 due to an cooling effect, and thusto lower a temperature of the refrigerating chamber 12, and when thesecond and third expanders 143 and 145 are opened and thus the secondrefrigerant is supplied, the second evaporator 250 serves to coolsurrounding air and air in the freezing chamber 13 due to the coolingeffect, and thus to lower a temperature of the freezing chamber 13.

In the first and second refrigeration systems 10 and 20, refrigerantswhich have different refrigeration capacities per unit volume may becirculated to perform a cooling operation.

The first refrigeration system 10 may further include blower fans 125and 155 which are provided at one side of the first condenser 120 or thefirst evaporator 150 to blow air. The blower fans 125 and 155 mayinclude a first condenser fan 125 which is provided at one side of thecondenser 120, and a first evaporator fan 155 which is provided at oneside of the evaporator 150.

Also, the second refrigeration system 20 may further include blower fans225 and 255 which are provided at one side of the second condenser 220or the second evaporator 250 to blow air.

The blower fans 225 and 255 may include a second condenser fan 225 whichis provided at one side of the second condenser 220, and a secondevaporator fan 255 which is provided at one side of the secondevaporator 250.

Heat exchanging performance of the first and second evaporators 150 and250 may be changed according to RPMs of the first and second evaporatorfans 155 and 255. For example, when more cold air is required due to anoperation of the first evaporator 150, the RPM of the first evaporatorfan 155 may be increased, and when the cold air is sufficient, the RPMof the first evaporator fan 155 may be reduced.

FIG. 3 is a view illustrating a partial structure of the refrigeratoraccording to the embodiment of the present disclosure, and FIG. 4 is across-sectional view taken along a line I-I′ of FIG. 1.

Referring to FIGS. 3 and 4, the refrigerator 1 according to theembodiment of the present disclosure may include a machinery chamber 30which is formed at the lower portion of the refrigerator 1, a firstrefrigeration chamber 31 which supplies the cold air to therefrigerating chamber 12, and a second refrigeration chamber 32 whichsupplies the cold air to the freezing chamber 13. The cold air of thefirst and second refrigeration chambers 31 and 32 may be discharged tothe refrigerating chamber 12 and the freezing chamber 13 through thecold air discharging part 18.

The first and second compressors 110 and 210 and the first and secondcondensers 120 and 220 may be installed at the machinery chamber 30.

The first refrigeration chamber 31 may be provided at a rear wall of therefrigerating chamber 12, and may be formed between the refrigeratingchamber inner case 16 and the refrigerating chamber cover plate 23. Thefirst evaporator 150, the subsidiary condenser 223, and the subsidiaryevaporator 153 may be installed at the first refrigeration chamber 31.

The first evaporator 150 may be in contact with the refrigeratingchamber cover plate 23, and may be fixed to the refrigerating chambercover plate 23 by a holder (not shown).

The heat exchange plate 190 may be provided between the subsidiarycondenser 223 and the subsidiary evaporator 153. The subsidiarycondenser 223, the subsidiary evaporator 153, and the heat exchangeplate 190 may be in contact with each other in order, and the subsidiarycondenser 223 may exchange heat with the subsidiary evaporator 153through the heat exchange plate 190.

The subsidiary evaporator 153 may be in contact with the refrigeratingchamber inner case 16. Also, the subsidiary evaporator 153 may be fixedby the holder (not shown) provided at the refrigerating chamber innercase 16, and the subsidiary condenser 223 may be fixed to the heatexchange plate 190.

As illustrated in the drawing, the subsidiary condenser 223 may bespaced from or in contact with the first evaporator 150.

A refrigerant pipe 150 a of the first evaporator 150, a refrigerant pipe153 a of the subsidiary evaporator 153, and a refrigerant pipe 223 a ofthe subsidiary condenser 223 may be bent and extend vertically.

Since the refrigerant pipe 150 a of the first evaporator 150, therefrigerant pipe 153 a of the subsidiary evaporator 153, and therefrigerant pipe 223 a of the subsidiary condenser 223 are verticallyinstalled adjacent to each other, an installation space for theplurality of devices forming the refrigeration cycle may be reduced.Therefore, a storage space of the storage chamber may be prevented frombeing reduced.

The second refrigeration chamber 32 may be provided at a rear wall ofthe freezing chamber 13, and may be formed between the freezing chamberinner case and the freezing chamber cover plate 24. The secondevaporator 250 may be installed at the second refrigeration chamber 32.

A gas-liquid separator 180 which filters a liquid refrigerant out of therefrigerant evaporated by the first and second evaporators 150 and 250and supplies a gas phase refrigerant to the first and second compressors110 and 210 may be provided at one side of each of the first and secondevaporators 150 and 250.

FIG. 5 is a control block diagram of the refrigerator according to theembodiment of the present disclosure, and FIG. 6 is a flowchartillustrating a method of controlling the refrigerator according to theembodiment of the present disclosure.

Referring to FIGS. 5 and 6, the refrigerator 1 according to theembodiment of the present disclosure may include a control part 50, aninput part 41 which allows a user to input a desired temperature of thefreezing chamber and a desired temperature of the refrigerating chamber,a refrigerating chamber temperature sensor 42 which detects atemperature of the refrigerating chamber 12, and a freezing chambertemperature sensor 43 which detects a temperature of the freezingchamber 13. The refrigerating chamber temperature sensor 42 and thefreezing chamber temperature sensor 43 may be referred to as a “firsttemperature sensor” and a “second temperature sensor,” and may becommonly called “temperature sensors.”

The control part 50 may control the first and second compressors 110 and210, the first and second condenser fans 125 and 225, the first andsecond evaporator fans 155 and 255, and the expanders 140 according towhether the temperatures detected by the temperature sensors 42 and 43satisfy the desired temperatures.

A method of controlling the refrigerator 1 according to whether tosatisfy the desired temperatures of the refrigerating chamber 12 and thefreezing chamber 13 will be described with reference to FIG. 6.

The refrigerator is operated, and the control part 50 performs controlso that the refrigeration cycle is circulated in the first refrigerationsystem 10. Specifically, the control part 50 may control the firstcompressor 110 and the first evaporator fan 155 to be driven, and mayalso control the first expander 141 to be opened (S1).

Also, the control part 50 performs control so that the refrigerationcycle is circulated in the second refrigeration system 20. Specifically,the control part 50 may control the second compressor 210 and the secondevaporator fan 255 to be driven, and may also control the second andthird expanders 143 and 145 to be opened (S2).

At this time, when a predetermined period of time passes after the firstcompressor 110 is driven, the second compressor 210 may be controlled tobe driven, such that the first refrigeration system 10 starts acirculation operation before the second refrigeration system 20. Forexample, after 3 minutes after the first compressor 110 is driven, thesecond compressor 210 may be controlled to be driven.

This is because circulation of the refrigerant occurs in the subsidiaryevaporator 153 before the subsidiary condenser 223, and thus the secondrefrigerant may be effectively condensed in the subsidiary condenser 223due to the air cooled while the first refrigerant is evaporated in thesubsidiary evaporator 153.

Then, the desired temperature input by the user is received through theinput part 41, and internal temperatures are detected by therefrigerating chamber temperature sensor 42 and the freezing chambertemperature sensor 43 (S3). A process of receiving the input of thedesired temperature and a process of detecting the internal temperaturemay be performed in a different order, and the process of receiving theinput of the desired temperature and detecting the internal temperaturemay be performed before the refrigeration cycle is driven.

First, by comparing the temperature detected by the refrigeratingchamber temperature sensor 42 with the desired temperature, it isdetermined whether the temperature of the refrigerating chamber 12satisfies the desired temperature (S4). The desired temperature may betemperature range information which does not have a lower limit. Thatis, the desired temperature information may be set so that thetemperature of the refrigerating chamber 12 is maintained to be acertain temperature or less.

When the temperature of the refrigerating chamber 12 satisfies thedesired temperature, i.e., the temperature of the refrigerating chamber12 is lower than the desired temperature, the control part 50 controlsthe refrigeration cycle of the first refrigeration system 10 to bestopped. Specifically, the control part 50 may control the firstcompressor 110 and the first evaporator fan 155 to be stopped, and alsomay control the first expander 141 to be closed (S5).

However, when the temperature of the refrigerating chamber 12 does notsatisfy the desired temperature, i.e., the temperature of therefrigerating chamber 12 is higher than the desired temperature, thecontrol part 50 controls the first and second refrigeration systems 10and 20 to be continuously circulated.

Then, by comparing the temperature detected by the freezing chambertemperature sensor 43 with the desired temperature, it is determinedwhether the temperature of the freezing chamber 13 satisfies the desiredtemperature (S6).

When the temperature of the freezing chamber 13 satisfies the desiredtemperature, i.e., the temperature of the freezing chamber 13 is lowerthan the desired temperature, the control part 50 controls therefrigeration cycle of the second refrigeration system 20 to be stopped.Specifically, the control part 50 may control the second compressor 210and the second evaporator 250 to be stopped, and also may control thesecond expander 143 or the third expander 145 to be closed. Even thoughone of the second and third expanders 143 and 145 is closed, thecirculation of the refrigerant in the second refrigeration system 20 maybe stopped (S7).

On the contrary, when the temperature of the freezing chamber 13 doesnot satisfy the desired temperature, i.e., the temperature of thefreezing chamber 13 is higher than the desired temperature, the controlpart 50 controls the first and second refrigeration systems 10 and 20 tobe continuously circulated.

A control process according to whether the temperature of therefrigerating chamber 12 satisfies the desired temperature, and acontrol process according to whether the temperature of the freezingchamber 13 satisfies the desired temperature may be performed in adifferent order, and the control processes may be performed at the sametime.

FIG. 7 is a graph illustrating a P-H diagram of the refrigerantcirculated in the refrigerator according to the embodiment of thepresent disclosure.

Referring to FIG. 7, R is a diagram representing a refrigerant cycle ofthe first refrigeration system 10, and F is a diagram representing arefrigerant cycle of the second refrigeration system 20.

When the first refrigerant is circulated in the first refrigerationsystem 10, the refrigeration cycle is circulated in order of A→B→C→D,and when the refrigerator 1 is in the “freezing chamber operation mode”,the refrigeration cycle is circulated in order of A′→B′→C′→D′→E→F. Wheneach of the first refrigerant and the second refrigerant has differentrefrigeration capacities per unit volume, there may be a difference in arefrigeration effect between the first and second refrigeration systems10 and 20, as illustrating in FIG. 7.

When the refrigerant is circulated in the first refrigeration system 10,an A-phase refrigerant inhaled into the first compressor 110 is changedinto a B-phase after compressed. And the refrigerant condensed by thefirst condenser 120 has a C-phase.

Then, the C-phase refrigerant is changed into a D-phase afterdepressurized by the first expander 141, and the refrigerant evaporatedby the subsidiary evaporator 153 and the first evaporator 150 has anA-phase.

Meanwhile, when the refrigerant is circulated in the secondrefrigeration system 20, an A′-phase refrigerant inhaled into the secondcompressor 210 is changed into a B′-phase after compressed. And therefrigerant condensed by the second condenser 220 has a C′-phase.

Then, the C′-phase refrigerant is introduced into the second expander143. The refrigerant introduced into and depressurized by the secondexpander 143 has a D′-phase.

The D′-phase refrigerant depressurized by the second expander 143 isintroduced into the subsidiary condenser 223, and then condensed oncemore. The refrigerant introduced into and condensed by the subsidiarycondenser 223 has an E-phase.

Then, the E-phase refrigerant condensed by the subsidiary condenser 223is introduced into the third expander 145, and depressurized once more.The refrigerant introduced into and depressurized by the third expander145 has an F-phase.

The F-phase refrigerant depressurized by the first expander 145 isintroduced into the second evaporator 250, and the refrigerantintroduced into and evaporated by the second evaporator 250 has anA′-phase. According to such a refrigeration cycle, an evaporationcapacity at the second evaporator 250 is h2-h1′.

In the subsidiary condenser 223, the refrigerant is condensed at a lowerpressure than that in the second condenser 220, and the second expander143 serves to prevent the radiant value of the condenser 220 from beingreduced due to the subsidiary condenser 223.

Meanwhile, in the case of the second refrigeration system 20, when thesecond expander 143 is not provided at the refrigeration cycle, theC-phase refrigerant condensed by the second condenser 220 and thesubsidiary condenser 223 is changed into a G-phase after depressurizedby the third expander 145, and the G-phase refrigerant is changed intothe A′-phase while being evaporated by the second evaporator 250.According to such a refrigeration cycle, the evaporation capacity at thesecond evaporator 250 is h2-h1.

Therefore, since the evaporation capacity when the second expander 143is provided at the refrigeration cycle is h2-h1′, and the evaporationcapacity when the second expander 143 is not provided at therefrigeration cycle is h2-h1, the evaporation capacity in the case inwhich the second expander 143 is provided may be increased by Ah,compared to that in the case in which the second expander 143 is notprovided.

Therefore, operation performance of the refrigerator may be improved,and a power consumption may be relatively reduced, compared with otherrefrigerators having the same operation performance. Eventually,operation efficiency of the refrigerator may be enhanced.

Hereinafter, a refrigerator according to another embodiment of thepresent disclosure will be described.

FIG. 8 is a system view illustrating a refrigeration cycle structure ofa refrigerator according to another embodiment of the presentdisclosure.

The refrigerator of the embodiment is different from that of theprevious embodiment in only the refrigerant cycle structure. Therefore,the description overlapping that of the previous embodiment will beomitted. Also, elements having the same or similar functions will begiven like reference numerals. The element having the same referencenumeral can quote the description in the previous embodiment, exceptparticular portions.

Referring to FIG. 8, the refrigerator 2 according to the embodiment ofthe present disclosure includes a plurality of devices for driving therefrigeration cycle.

Specifically, the refrigerator 2 may include a compressor 310 whichcompresses a refrigerant, a condenser 320 which condenses therefrigerant compressed by the compressor 310, a plurality of expanders341, 343, and 345 which depressurize the refrigerant condensed by thecondenser 320, a plurality of evaporators 350, 353, and 360 whichevaporate the refrigerant depressurized by the plurality of expanders341, 343, and 345, and a subsidiary condenser 323 which condenses therefrigerant depressurized by one of the plurality of expanders 341, 343,and 345.

The refrigerator 2 includes a refrigerant pipe 300 which connects thecompressor 310, the condenser 320, the expanders 341, 343, and 345, andthe evaporators 350 and 360 to guide a flow of the refrigerant.

The plurality of evaporators 350, 353, and 360 include a firstevaporator 360 which generates cold air supplied to one of therefrigerating chamber 12 and the freezing chamber 13, a secondevaporator 350 which generates the cold air supplied to the otherstorage chamber, and a cold storage evaporator 353 which is installedadjacent to the subsidiary condenser 323. The subsidiary condenser 323may be in contact with the cold storage evaporator 353. The firstevaporator 360 may be referred to as a “freezing chamber evaporator,”and the second evaporator 350 may be referred to as a “refrigeratingchamber evaporator.”

The first evaporator 360 may generate the cold air supplied to thefreezing chamber 13, and may be disposed at one side of the freezingchamber 13. The second evaporator 350 may generate the cold air suppliedto the refrigerating chamber 12, and may be disposed at one side of therefrigerating chamber 12.

A temperature of the cold air supplied to the freezing chamber 13 may belower than that of the cold air supplied to the refrigerating chamber12, and thus a refrigerant evaporation pressure of the first evaporator360 may be lower than that of the second evaporator 350.

The refrigerant pipe 300 at exit sides of the first and secondevaporators 360 and 350 extends to an entrance side of the compressor310. Therefore, the refrigerant passing through the first and secondevaporators 360 and 350 may be introduced into the compressor 310.

The refrigerator 2 may further include a cold storage part 370 whichsurrounds the subsidiary condenser 323 and the cold storage evaporator353, and exchanges heat with the subsidiary condenser 323 or the coldstorage evaporator 353.

It may be understood that the cold storage part 370 is an indirectcooling unit for cooling the refrigerating chamber 12. Specifically, thecold storage part 370 includes a case 371 which defines a storage space,and a cold storage material 372 which is stored in an inside of the case371.

The cold storage material 372 may include a phase change material (PCM)of which a phase is changed at a low temperature to accomplish a coolingeffect. For example, the PCM may include water or carbon dioxide.

When the PCM is used as the cold storage material, high density cold airmay be stored through an inflow and outflow of a large quantity of coldair during a phase changing process, while a predetermined targettemperature is maintained. Also, since a setting temperature may bemaintained for a long period of time without external power supply, itis possible to contribute to energy saving.

The cold storage evaporator 353 may be installed at an inside of thecase 371 of the cold storage part 370 to evaporate the refrigerant andthus to store the cold air in the cold storage material 372, and thesubsidiary condenser 323 may condense the refrigerant using the cold airstored in the cold storage material 372. Also, the subsidiary condenser323 may be directly in contact with the cold storage evaporator 353 toperform a heat exchanging operation therewith and thus to condense therefrigerant.

The refrigerator 2 includes first and second branch passages 301 and 302which branch the refrigerant passing through the condenser 320. Thefirst and second branch passages 301 and 302 are branched from therefrigerant pipe 300.

The refrigerator 2 may further include a valve device 330 which isinstalled at the refrigerant pipe 300 to branch the refrigerant into thefirst and second branch passages 301 and 302.

The valve device 330 may include a three-way valve having one inlet portthrough which the refrigerant is introduced, and two outlet portsthrough which the refrigerant is discharged. The one inlet port isconnected to the refrigerant pipe 300, and a first outlet port of thetwo outlet ports is connected to the first branch passage 301, and asecond outlet port is connected to the second branch passage 302. Atleast one of the first and second outlet ports may be opened accordingto control of the valve device 330, and thus a flow route of therefrigerant may be changed.

The second evaporator 350 may be installed at an exit side of the coldstorage evaporator 353 on the first branch passage 301.

The first evaporator 360 and the third expander 345 installed at anentrance side of the first evaporator 360 to expand the refrigerant maybe provided at the second branch passage 302. The third expander 345 mayinclude a capillary tube. The third expander 345 is referred to as a“first evaporation expander.”

The first expander 341 and the cold storage evaporator 353 installed atan exit side of the first expander 341 to evaporate the refrigerantdepressurized by the first expander 341 may be installed at the firstbranch passage 301. The first expander 341 may include a capillary tube.

The refrigerant flows through the first branch passage 301 and then isintroduced into the cold storage evaporator 353, and the cold air may bestored in the PCM while the refrigerant is evaporated in the coldstorage evaporator 353. The first expander 341 is referred to as a“second evaporation expander.”

In order for the refrigerant evaporation pressure of the firstevaporator 360 to be formed lower than that of the second evaporator350, a diameter of the capillary tube of the third expander 345 may besmaller than that of the capillary tube of the first expander 341.

The third expander 345, the subsidiary condenser 323 which is installedat an entrance side of the third expander to condense the refrigerant,and the second expander 343 which is installed at an entrance side ofthe subsidiary condenser 323 to depressurize the refrigerant condensedby the condenser 320 may be installed at the second branch passage 302.The second expander 343 may include a capillary tube, and may bereferred to as a “condensing expander,” because the second expander 343performs a depressurizing operation for a subsidiary condensingoperation.

The cooling performance may be enhanced by depressurizing therefrigerant condensed in the condenser 320 and then condensing therefrigerant in the subsidiary condenser 323 (referring to FIG. 14).

The valve device 330 may be controlled so that the flow route of therefrigerant is changed according to an operation mode of therefrigerator. Here, the operation mode of the refrigerator may include a“simultaneous operation mode” in which the cooling operations of therefrigerating chamber and the freezing chamber are performed, a“refrigerating chamber operation mode” in which the cooling operation ofthe refrigerating chamber is performed, a “freezing chamber operationmode” in which the cooling operation of the freezing chamber isperformed, and a “cold storage operation mode” in which the cold energyis stored in the cold storage part 370. The “cold storage operationmode” may be simultaneously performed with the “refrigerating chamberoperation mode.”

As an example, when the simultaneous operation mode is performed, thevalve device 330 may be controlled so that the refrigerant is branchedand supplied to the first and second branch passages 301 and 302. Thatis, the valve device 330 may be operated so that all of the two outletports are opened.

As another example, when the refrigerating chamber operation mode isperformed, the refrigerant is supplied to the second evaporator 350. Andthe valve device 330 may be controlled so that the refrigerant isbranched and supplied to the first branch passage 301. That is, thevalve device 330 may be operated so that the first outlet port connectedto the first branch passage 301 is opened.

When the first outlet port is opened, the refrigerant passes through thefirst branch passage 301, is depressurized by the first expander 341,flows to the cold storage evaporator 353 to be evaporated and thus tostore the cold air in the cold storage material 372, and then flows tothe second evaporator 350. Then, while the refrigerant is evaporated atthe second evaporator 350, peripheral heat is absorbed to cool the air.

As still another example, when the freezing chamber operation mode isperformed, the refrigerant is supplied to the first evaporator 360. Andthe valve device 330 may be controlled so that the second outlet portconnected to the second branch passage 302 is opened.

When the second outlet port is opened, the refrigerant passes throughthe second branch passage 302, is depressurized by the second expander343, flows to the subsidiary condenser 323 to be condensed, and thenflows to the first evaporator 360. Then, while the refrigerant isevaporated at the first evaporator 360, the peripheral heat is absorbedto cool the air.

As yet another example, when the cold storage operation mode isperformed, the flow of the refrigerant and the operation of the valvedevice 330 are the same as those in the refrigerating chamber operationmode, but as described later, there is a difference in only whether theevaporator fan is operated.

The above described operation mode may be performed based on whether tosatisfy the internal temperature of the refrigerator 2, and a detailedmethod according to whether to satisfy the internal temperature may bedescribed later with reference to FIG. 12.

Meanwhile, the refrigerator 2 may include blower fans 325, 355 and 365which are respectively provided at one side of the heat exchanger toblow the air. The blower fans 325, 355, and 365 include a condenser fan325 which is provided at one side of the condenser 320, a firstevaporator fan 355 which is provided at one side of the secondevaporator 350, and a second evaporator fan 365 which is provided at oneside of the first evaporator 360.

Heat exchanging performance of the first and second evaporators 350 and360 may be changed according to RPMs of the first and second evaporatorfans 355 and 365. For example, when more cold air is required due to anoperation of the second evaporator 350, the RPM of the first evaporatorfan 355 may be increased, and when the cold air is sufficient, the RPMof the first evaporator fan 355 may be reduced.

FIG. 9 is a view illustrating a partial structure of the refrigeratoraccording to another embodiment of the present disclosure, and FIG. 10is a longitudinal cross-sectional view of the refrigerator according toanother embodiment of the present disclosure.

Referring to FIGS. 9 and 10, the refrigerator 2 according to anotherembodiment of the present disclosure may include a machinery chamber 30which is formed at a lower portion of the refrigerator 2, a firstrefrigeration chamber 31 which supplies the cold air to therefrigerating chamber 12, and a second refrigeration chamber 32 whichsupplies the cold air to the freezing chamber 13. The cold air of thefirst and second refrigeration chamber 31 and 32 may be discharged tothe refrigerating chamber 12 and the freezing chamber 13 through thecold air discharging part 18.

The compressor 310 and the condenser 320 may be installed at themachinery chamber 30.

The first refrigeration chamber 31 may be provided at a rear wall of therefrigerating chamber 12, and may be formed between the refrigeratingchamber inner case 16 and the refrigerating chamber cover plate 23. Thesecond evaporator 350, the cold storage part 370, and the subsidiarycondenser 323 and the cold storage evaporator 353 which are provided atan inside of the cold storage part 370 may be installed at the firstrefrigeration chamber 31.

The second evaporator 350 may be in contact with the refrigeratingchamber cover plate 23, and may be fixed thereto by a holder (notshown).

The cold storage part 370 may be in contact with the refrigeratingchamber inner case 16, and may be fixed thereto by a holder (not shown).The second evaporator 350 and the cold storage part 370 may be spacedfrom each other, as illustrated in the drawing. However, the secondevaporator 350 may be in contact with the cold storage part 370.

A refrigerant pipe 350 a of the second evaporator 350, a refrigerantpipe 353 a of the cold storage evaporator 353 and a refrigerant pipe 323a of the subsidiary condenser 323 may be bent and extend vertically.

Since the refrigerant pipe 350 a of the second evaporator 350, therefrigerant pipe 353 a of the cold storage evaporator 353 and therefrigerant pipe 323 a of the subsidiary condenser 323 are installedadjacent to each other, an installation space for the plurality ofdevices forming the refrigeration cycle may be reduced. Thus, a storagespace of the storage chamber may be prevented from being reduced.

The second refrigeration chamber 32 may be provided at a rear wall ofthe freezing chamber 13, and may be formed between the freezing chamberinner case and the freezing chamber cover plate 24. The first evaporator360 may be installed at the second refrigeration chamber 32.

A gas-liquid separator 180 which filters a liquid refrigerant out of therefrigerant evaporated by the first and second evaporators 350 and 360and supplies a gas phase refrigerant to the compressors 310 may beprovided at one side of each of the first and second evaporators 350 and360.

FIG. 11 is a control block diagram of the refrigerator according toanother embodiment of the present disclosure, and FIGS. 12 and 13 areflowcharts illustrating a method of controlling the refrigeratoraccording to the embodiment of the present disclosure.

Referring to FIGS. 11 to 13, the refrigerator 2 according to theembodiment of the present disclosure may include a control part 50, aninput part 41 which allows a user to input a desired temperature of thefreezing chamber and a desired temperature of the refrigerating chamber,a refrigerating chamber temperature sensor 42 which detects atemperature of the refrigerating chamber 12, and a freezing chambertemperature sensor 43 which detects a temperature of the freezingchamber 13. The refrigerating chamber temperature sensor 42 and thefreezing chamber temperature sensor 43 may be referred to as a “firsttemperature sensor” and a “second temperature sensor”.

The control part 50 may control the compressor 310, the condenser fan325, the first evaporator fan 355, the second evaporator fan 365 and thevalve device 330 according to whether the temperatures detected by thetemperature sensors 42 and 43 satisfy the desired temperatures.

A method of controlling the refrigerator 2 according to whether tosatisfy the desired temperature of the refrigerating chamber 12 will bedescribed with reference to FIG. 12.

The refrigerator is operated, and the desired temperature input by theuser is received through the input part 41, and the temperature of therefrigerating chamber 12 is detected by the refrigerating chambertemperature sensor 42 (S11). A process of receiving the input of thedesired temperature and a process of detecting the temperature may beperformed in a different order.

By comparing the temperature detected by the refrigerating chambertemperature sensor 42 with the desired temperature, it is determinedwhether the temperature of the refrigerating chamber 12 satisfies thedesired temperature (S12). The desired temperature may be temperaturerange information which does not have a lower limit. That is, thedesired temperature information may be set so that the temperature ofthe refrigerating chamber 12 is maintained to be a certain temperatureor less.

When the temperature of the refrigerating chamber 12 satisfies thedesired temperature, the control part 50 controls the refrigerationcycle to be stopped (S13). Specifically, the control part 50 may controlthe compressor 310 and the first evaporator fan 355 to be stopped (S14).

As described above, when the refrigeration cycle is stopped, a coolingeffect due to the refrigeration cycle does not occur, and the internaltemperature of the refrigerator may be maintained in a certain level dueto an indirect cooling effect by the cold storage part 370.

However, when the temperature of the refrigerating chamber 12 does notsatisfy the desired temperature, the control part 50 controls therefrigerator 2 to be driven in the refrigerating chamber operation mode,and at the same time, a cold storage operation is also performed (S15).Specifically, the control part 50 may control the compressor 310 and thefirst evaporator fan 355 to be driven (S16). Also, the valve device 330is controlled so that the first outlet port is opened and the secondoutlet port is closed (S17).

Therefore, the refrigerant may flow to the cold storage evaporator 353and the second evaporator 350. Specifically, when the refrigerantdepressurized by the first expander 341 is evaporated in the coldstorage evaporator 353, the cold storage operation in which the cold airis stored in the cold storage material is performed, and when therefrigerant passing through the cold storage evaporator 353 isevaporated in the second evaporator 350, the refrigerating chamberoperation mode in which the air flowing in the first refrigerationchamber 31 is cooled is performed.

When the control according to whether the temperature of therefrigerating chamber 12 satisfies the desired temperature is finished,another control according to whether the temperature of the freezingchamber 13 satisfies the desired temperature may be performed. Adetained control method according to whether the temperature of thefreezing chamber 13 satisfies the desired temperature will be describedwith reference to FIG. 13.

The refrigerator is operated, and the desired temperature input by theuser is received through the input part 41, and the temperature of thefreezing chamber 13 is detected by the freezing chamber temperaturesensor 43 (S21). A process of receiving the input of the desiredtemperature and a process of detecting the temperature may be performedin a different order.

By comparing the temperature detected by the freezing chambertemperature sensor 43 with the desired temperature, it is determinedwhether the temperature of the freezing chamber 13 satisfies the desiredtemperature (S22). The desired temperature may be set so that thetemperature of the freezing chamber 13 is maintained below a certaintemperature.

When the temperature of the freezing chamber 13 satisfies the desiredtemperature, the control part 50 controls the refrigeration cycle to bestopped (S23). Specifically, the control part 50 may control thecompressor 310 and the first evaporator fan 355 to be stopped (S24).Also, the valve device 330 may be controlled so that the first andsecond outlet ports are closed (S25).

However, when the temperature of the freezing chamber 13 does notsatisfy the desired temperature, the control part 50 controls therefrigerator 2 to be driven in the freezing chamber operation mode(S26). Specifically, the control part 50 may control the compressor 310and the second evaporator fan 365 to be driven (S27). Also, the valvedevice 330 is controlled so that the second outlet port is opened andthe first outlet port is closed (S28).

Therefore, the refrigerant may flow to the subsidiary condenser 323 andthe first evaporator 360. Specifically, the refrigerant depressurized bythe second expander 343 is condensed in the subsidiary condenser 323,and the refrigerant passing through the subsidiary condenser 323 isdepressurized again in the third expander 345 and then evaporated in thefirst evaporator 360, and thus the air flowing in the secondrefrigeration chamber 32 is cooled. In the subsidiary condenser 323, therefrigerant is condensed at a lower pressure than that in the condenser320. Since a condensing and expanding process of the refrigerant isadded, the cooling efficiency may be increased, and a detailed principlethereof will be described in FIG. 14.

A control process according to whether the temperature of therefrigerating chamber 12 satisfies the desired temperature, and acontrol process according to whether the temperature of the freezingchamber 13 satisfies the desired temperature may be performed in adifferent order, and the control processes may be performed at the sametime. At this time, when both of the temperatures of the refrigeratingchamber 12 and the freezing chamber 13 do not satisfy the desiredtemperatures, the simultaneous operation mode in which the refrigerantsimultaneously flows to the first and second evaporators 350 and 360 maybe performed. At this time, the flow of the refrigerant in each of therefrigerating chamber operation and the freezing chamber refrigerationoperation quotes the description in the refrigerating chamber operationmode and the freezing chamber operation mode.

FIG. 14 is a graph illustrating a P-H diagram of the refrigerantcirculated in the refrigerator according to another embodiment of thepresent disclosure.

Referring to FIG. 14, R is a diagram representing a refrigerant cycle inthe refrigerating chamber operation mode, and F is a diagramrepresenting a refrigerant cycle in the freezing chamber operation mode.

When the refrigerator 2 is in the “refrigerating chamber operationmode,” the refrigeration cycle is circulated in order of A→B→C→D, andwhen the refrigerator 2 is in the “freezing chamber operation mode,” therefrigeration cycle is circulated in order of A′→B′→C′→D′→E→F.

In the case of the refrigerating chamber operation mode, an A-phaserefrigerant inhaled into the compressor 310 is changed into a B-phaseafter compressed. And the refrigerant condensed by the condenser 320 hasa C-phase.

Then, the refrigerant passing through the valve device 330 anddepressurized by the first expander 341 has a D-phase, and therefrigerant evaporated in the cold storage evaporator 353 and the secondevaporator 350 has an A-phase.

Meanwhile, in the case of the freezing chamber operation mode, anA′-phase refrigerant inhaled into the compressor 310 is changed into aB′-phase after compressed. And the refrigerant condensed by thecondenser 320 has a C-phase.

And the C-phase refrigerant passes through the valve device 330 and isintroduced into the second expander 343. The refrigerant introduced intoand depressurized by the second expander 343 has a D′-phase.

The D′-phase refrigerant depressurized in the second expander 343 isintroduced into the subsidiary condenser 323 and then condensed oncemore. The refrigerant introduced into and condensed by the subsidiarycondenser 323 has an E-phase.

Then, the E-phase refrigerant condensed in the subsidiary condenser 323is introduced into the third expander 345 and condensed once more. Therefrigerant introduced into and depressurized by the third expander 345has an F-phase.

The F-phase refrigerant depressurized in the first expander 341 isintroduced into the first evaporator 360, and the refrigerant introducedinto and evaporated by the first evaporator 360 has an A′-phase.According to such a refrigeration cycle, an evaporation capacity at thefirst evaporator 360 is h2-h1′.

In the subsidiary condenser 323, the refrigerant is condensed at a lowerpressure than that in the condenser 320, and the second expander 343serves to prevent the radiant value of the condenser 320 from beingreduced due to the subsidiary condenser 323.

Meanwhile, in the refrigerating chamber operation mode, when the secondexpander 343 is not provided at the refrigeration cycle, the C-phaserefrigerant condensed by the condenser 320 and the subsidiary condenser323 is changed into a G-phase after depressurized by the third expander345, and the G-phase refrigerant is changed into the A′-phase whilebeing evaporated by the first evaporator 360. According to such arefrigeration cycle, the evaporation capacity at the first evaporator360 is h2-h1.

Therefore, since the evaporation capacity, when the second expander 343is provided at the refrigeration cycle, is h2-h1′, and the evaporationcapacity when the second expander 343 is not provided at therefrigeration cycle is h2-h1, the evaporation capacity in the case inwhich the second expander 343 is provided may be increased by Ah,compared to that in the case in which the second expander 343 is notprovided.

Therefore, operation performance of the refrigerator may be improved,and a power consumption may be relatively reduced, compared with otherrefrigerators having the same operation performance. Eventually,operation efficiency of the refrigerator may be enhanced.

Hereinafter, a refrigerator according to still another embodiment willbe described.

FIG. 15 is a view illustrating an internal structure of a refrigeratoraccording to still another embodiment of the present disclosure.

In the refrigerator according to the embodiment, the descriptionoverlapped with the previous embodiment will be omitted. Also, elementshaving the same or similar functions will be given like referencenumerals. The element having the same reference numeral can quote thedescription in the previous embodiment, except particular portions.

Referring to FIG. 15, the refrigerator 3 according to the embodiment ofthe present disclosure includes a main body 61 of which a front surfaceis opened, and a storage chamber which is formed at an inside of themain body 61. The storage chamber includes a freezing chamber 62 and arefrigerating chamber 63. The freezing chamber 62 and the refrigeratingchamber 63 may be divided by a division part 64.

The main body 61 may include an outer case 65 which defines an exteriorof the refrigerator 3, a freezing chamber inner case 66 which isdisposed at an inside of the outer case 65 to form an inner surface ofthe freezing chamber 62, and a refrigerating chamber inner case 67 whichis disposed at the inside the outer case 65 to form an inner surface ofthe refrigerating chamber 63. The freezing chamber inner case 66 and therefrigerating chamber inner case 67 may be commonly referred to as“inner cases”.

Also, the refrigerator 3 may further include a freezing chamber door 71and a refrigerating chamber door 72 which are rotatably coupled to afront side of the main body 61 to selectively open and close thefreezing chamber 62 and the refrigerating chamber 63.

In the embodiment, a side-by-side type in which the freezing chamber andthe refrigerating chamber are provided at left and right sides thereofwill be described as an example. However, the spirit of the presentdisclosure may be applied to not only the above-described structure ofthe refrigerator, but also a top mount type in which the freezingchamber is formed at an upper portion thereof and the refrigeratingchamber is formed at a lower portion thereof, or a bottom freezer typein which the freezing chamber is formed at a lower portion thereof andthe refrigerating chamber is formed at an upper portion thereof.

The freezing chamber 62 may include a freezing chamber damper 82 throughwhich air cooled by an evaporator 450 (referring to FIG. 16) which willbe described later is discharged to the freezing chamber 62. Thefreezing chamber damper 82 may be provided at a rear surface of thefreezing chamber 62, and may be formed at the freezing chamber coverplate 73. The evaporator 450 is disposed at a rear side of the freezingchamber cover plate 73.

A refrigerating chamber cover plate 74 having a cold air dischargingpart (not shown) through which cold air is discharged may be alsoprovided at a rear surface of the refrigerating chamber 63.

FIG. 16 is a transverse cross-sectional view taken along a line I-I′ ofFIG. 15, FIG. 17 is a longitudinal cross-sectional view taken along aline II-IF of FIG. 15, and FIG. 18 is a view illustrating arefrigeration cycle structure of the refrigerator according to stillanother embodiment of the present disclosure.

Referring to FIGS. 16 to 18, the refrigerator 3 according to theembodiment of the present disclosure may include a refrigeration chamber81 which is provided at an inside of the refrigerator 3, the evaporator450 which is installed at the refrigeration chamber 81 to evaporate arefrigerant, a refrigerating chamber damper 69 which controls a flow ofthe air cooled by the evaporator 450 in the refrigerating chamber 63,the freezing chamber damper 82 which controls a flow of the air cooledby the evaporator 450 in the freezing chamber 62, and a cold storagepart 460 which is installed between the refrigerating chamber inner case67 and the refrigerating chamber cover plate 74. The cold storage part460 may be fixed to the refrigerating chamber cover plate 74 by a holder(not shown), but is not limited thereto.

The refrigerating chamber damper 69 may be installed at the divisionpart 64 which divides the freezing chamber 62 and the refrigeratingchamber 63. When the refrigerating chamber damper 69 is opened, the coldair in the refrigeration chamber 81 may be introduced into therefrigerating chamber 63 through the refrigerating chamber damper 69.

It may be understood that the cold storage part 460 is an indirectcooling unit for cooling the refrigerating chamber 63. Specifically, thecold storage part 460 includes a case 461 which defines a storage space,and a cold storage material 462 which is stored at an inside of the case461.

The cold storage material 462 may include a phase change material (PCM)of which a phase is changed at a low temperature to perform a coolingoperation. For example, the PCM may include water or carbon dioxide.

When the PCM is used as the cold storage material, high density cold airmay be stored through an inflow and outflow of a large quantity of coldair during a phase changing process, while a predetermined targettemperature is maintained. Also, since a setting temperature may bemaintained for a long period of time without external power supply, itis possible to contribute to energy conservation.

A cold storage evaporator 451 which evaporates the refrigerant to storecold air in the cold storage material 462, and a subsidiary condenser421 in which the refrigerant is condensed by the cold storage material462 may be installed at an inside of the case 461 of the cold storagepart 460.

A refrigerant pipe 451 a of the cold storage evaporator 451 may be bentand extend vertically. And a refrigerant pipe 421 a of the subsidiarycondenser 421 may be bent and extend vertically.

Since the refrigerant pipe 451 a of the cold storage evaporator 451, therefrigerant pipe 421 a of the subsidiary condenser 421 are verticallyinstalled adjacent to each other, an installation space for the coldstorage evaporator 451 and the subsidiary condenser 421 may be reduced.Thus, a storage space of the storage chamber may be prevented from beingreduced.

A machinery chamber 80 may be formed at the lower portion of therefrigerator 3. A compressor 410 which compresses the refrigerantevaporated in the evaporator 450 and a condenser 420 which condenses therefrigerant compressed in the compressor 410 may be included at aninside of the machinery chamber 80.

The refrigerator 3 includes a refrigerant pipe 400 which connects thecompressor 410 and the condenser 420 so as to guide the flow of therefrigerant.

The refrigerator 3 includes first and second branch passages 401 and 402which branch the refrigerant passing through the condenser 420. Therefrigerator 3 includes a valve device 430 which is installed at therefrigerant pipe 400 to branch the refrigerant into the first and secondbranch passages 401 or 402. The valve device 430 may include a three-wayvalve having one inlet port through which the refrigerant is introduced,and two outlet ports through which the refrigerant is discharged. Theone inlet port is connected to the refrigerant pipe 400, and a firstoutlet port of the two outlet ports is connected to the first branchpassage 401, and a second outlet port is connected to the second branchpassage 402. At least one of the first and second outlet ports may beopened according to a control operation of the valve device 330, andthus a flow route of the refrigerant may be changed.

The cold storage evaporator 451 which evaporates the refrigerant and thefirst and a first expander 441 which is installed at an entrance side ofthe cold storage evaporator 451 may be installed at the first branchpassage 401. The first expander 441 may include a capillary tube.

When the refrigerant condensed by the condenser 420 flows through thefirst branch passage 401 and then is introduced into the cold storageevaporator 451, the cold energy may be stored in the PCM while therefrigerant is evaporated in the cold storage evaporator 451. The firstexpander 441 is referred to as a “cold storage expander.”

The subsidiary condenser 421 which condenses the refrigerant and thesecond expander 442 which is installed at an entrance side of thesubsidiary condenser 421 to depressurize the refrigerant may beinstalled at the second branch passage 402. The second expander 442 mayinclude a capillary tube, and may be referred to as a “condensingexpander”, because the second expander 343 performs a depressurizingoperation for a subsidiary condensing operation.

When the refrigerant condensed in the condenser 420 flows through thesecond branch passage 402, and is then introduced into the subsidiarycondenser 421, the cooling performance may be enhanced by depressurizingthe refrigerant condensed in the condenser 420 and then condensing therefrigerant in the subsidiary condenser 421 (referring to FIG. 19).

The evaporator 450 which is installed at the entrance side of thesubsidiary condenser 421 and a third expander 443 which is installed atan entrance side of the evaporator 450 may be installed at the secondbranch passage 402. The third expander 443 may include a capillary tube.The third expander 443 is referred to as an “evaporation expander”.

A control operation of the valve device 430 may be performed based onwhether an internal temperature of the refrigerator 3 satisfies thedesired temperature.

When the internal temperature of the refrigerator 3 satisfies thedesired temperature, the refrigerator 3 is controlled to perform a “lowcold energy operation” in which cold air is stored in the cold storagematerial 462. Specifically, the valve device 430 is controlled so thatthe first outlet port is opened and thus the refrigerant flows to thecold storage evaporator 451 through the first branch passage 401. Atthis time, the second outlet port may be closed.

However, when the internal temperature of the refrigerator 3 does notsatisfy the desired temperature, the refrigerator 3 is controlled toperform a “high cold energy operation.” Specifically, the valve device430 is controlled so that the second outlet port is opened and thus therefrigerant flows to the second branch passage 402. At this time, thefirst outlet port may be closed.

A detailed control method in the high cold air operation or the low coldair operation will be described in FIG. 21.

The refrigerant evaporated in the evaporator 450 is introduced into thecompressor 410, and a check valve 470 which prevent a back flow of therefrigerant may be installed at the refrigerant pipe 400 between theevaporator 450 and the compressor 410.

The refrigerator 3 may further include blower fans 425 and 455 which areprovided at one side of the condenser 420 or the evaporator 450 to blowthe air. The blower fans 425 and 455 includes a condenser fan 425 whichis provided at one side of the condenser 420, and an evaporator fan 455which is provided at one side of the evaporator 450.

Heat exchanging performance of the evaporator 450 may be changedaccording to an RPM of the evaporator fan 455. For example, when morecold air is required due to an operation of the evaporator 450, the RPMof the evaporator fan 455 may be increased, and when the cold air issufficient, the RPM of the evaporator fan 455 may be reduced.

FIG. 19 is a graph illustrating a P-H diagram of a refrigerantcirculated in the refrigerator according to still another embodiment ofthe present disclosure.

Referring to FIGS. 18 and 19, when the refrigerator according to theembodiment of the present disclosure performs the “low cold airoperation,” the refrigeration cycle is circulated in order of A→B→C→D.At this time, it is assumed that performance of the cold storageevaporator 451 is the same as that of the evaporator 450, andperformance of the first expander 441 is the same as that of the thirdexpander 443. Therefore, it may be understood that the two cycles aredifferent from each other in whether the second expander 442 and thesubsidiary condenser 421 are installed.

Specifically, an A-phase refrigerant introduced into the compressor 410is changed into a B-phase after compressed. And the refrigerantcondensed by the condenser 420 has a C-phase.

Then, the refrigerant passing through the valve device 430 anddepressurized by the first expander 441 has a D-phase, and therefrigerant depressurized by the first expander 441 is introduced intothe cold storage evaporator 451, and the refrigerant evaporated by thecold storage evaporator 451 has an A-phase.

According to such as refrigeration cycle, an evaporation capacity at thecold storage evaporator 450 is h2-h1. This is a result when it isassumed that the performance of the cold storage evaporator 451 is thesame as that of the evaporator 450.

However, when the first expander 441 is provided at the refrigerationcycle, i.e., the “high cold energy operation” is performed, therefrigeration cycle is circulated in order of A→B→C→D′→E→F.

Specifically, an A-phase refrigerant introduced into the compressor 410is changed into a B-phase after compressed. And the B-phase refrigerantis introduced into and condensed by the first condenser 120, and thenchanged into a C-phase.

Then, the C-phase refrigerant passes through the valve device 430 and isintroduced into the second expander 442. The refrigerant introduced intoand depressurized by the second expander 442 has a D′-phase.

The D′-phase refrigerant depressurized by the second expander 442 isintroduced into the subsidiary condenser 421, and then condensed oncemore. The refrigerant introduced into and condensed by the subsidiarycondenser 421 has an E-phase.

Then, the refrigerant condensed by the subsidiary condenser 421 isintroduced into the first expander 441, and depressurized once more. Therefrigerant introduced into the third expander 443 and depressurized hasan F-phase.

The F-phase refrigerant depressurized by the third expander 443 isintroduced into the evaporator 450, and the refrigerant introduced intoand evaporated by the evaporator 450 has an A-phase.

In the subsidiary condenser 421, the refrigerant is condensed at a lowerpressure than that in the condenser 420, and the second expander 442serves to prevent the radiant value of the condenser 420 from beingreduced due to the subsidiary condenser 421.

According to such as refrigeration cycle, an evaporation capacity at theevaporator 450 is h2-h1′.

It can be understood that h2-h1′ which is the evaporation capacity atthe evaporator 450 is larger than h2-h1 which is the evaporationcapacity at the cold storage evaporator 451 by Ah due to thedepressurizing operation of the refrigerant in the second expander 442.Since this is a result when it is assumed that the performance of thecold storage evaporator 451 is the same as that of the evaporator 450,and the performance of the first expander 441 is the same as that of thethird expander 443, it may be understood that the evaporation capacityis increased by adding the second expander 442 to the refrigerationcycle, and the cooling efficiency is also increased.

Therefore, operation performance of the refrigerator may be improved,and a power consumption may be relatively reduced, compared with otherrefrigerators having the same operation performance. Eventually,operation efficiency of the refrigerator may be enhanced.

FIG. 20 is a control block diagram of the refrigerator according tostill another embodiment of the present disclosure.

Referring to FIG. 20, the refrigerator 3 according to the embodiment ofthe present disclosure may include a control part 50, an input part 41which allows a user to input a desired temperature of the freezingchamber and a desired temperature of the refrigerating chamber, afreezing chamber temperature sensor 43 which detects a temperature ofthe freezing chamber 62, and a refrigerating chamber temperature sensor42 which detects a temperature of the refrigerating chamber 63. Thefreezing chamber temperature sensor 43 and the refrigerating chambertemperature sensor 42 may be commonly called “temperature sensors”.

The control part 50 may control the compressor 410, the condenser fan425, the valve device 430, the evaporator fan 455, the freezing chamberdamper 82 and the refrigerating chamber damper 69 according to whetherthe temperatures detected by the temperature sensors 42 and 43 satisfythe desired temperatures.

The control part 50 may primarily control the freezing chamber damper 82and the refrigerating chamber damper 69 according to whether thetemperatures detected by the temperature sensors 42 and 43 satisfy thedesired temperatures, and thus may control the internal temperature ofthe refrigerator.

Specifically, when the temperature detected by the freezing chambertemperature sensor 43 does not satisfy the desired temperatures, thecontrol part 50 may control the freezing chamber damper 82 to bemaximally opened, and thus the cold air is introduced into the freezingchamber 62. When the temperature detected by the freezing chambertemperature sensor 43 satisfies the desired temperatures, the controlpart 50 may control the freezing chamber damper 82 so that the cold airis not introduced into the freezing chamber 62.

Also, when the temperature detected by the refrigerating chambertemperature sensor 42 does not satisfy the desired temperatures, thecontrol part 50 may control the refrigerating chamber damper 60 to bemaximally opened, and thus the cold air is introduced into therefrigerating chamber 63. When the temperature detected by therefrigerating chamber temperature sensor 42 satisfies the desiredtemperatures, the control part 50 may control the refrigerating chamberdamper 69 so that the cold air is not introduced into the refrigeratingchamber 63.

Meanwhile, when the temperatures detected by the temperature sensors 42and 43 do not satisfy the desired temperatures even though the dampers82 and 69 are controlled, the control part 50 may control the compressor410, the condenser fan 425, the valve device 430 and the evaporator fan455, and thus may control the refrigeration cycle to perform the highcold energy operation or the low cold energy operation. A detailedcontrol method thereof will be described in FIG. 21.

FIG. 21 is a flowchart illustrating a method of controlling therefrigerator according to still another embodiment of the presentdisclosure. The method of controlling the refrigerator according tostill another embodiment of the present disclosure will be describedwith reference to FIG. 21.

When an operation the refrigerator 3 is started, the control part 50drives the compressor 410, and thus the refrigeration cycle iscirculated (S31).

Then, the desired temperatures of the refrigerating chamber and thefreezing chamber are input and received through the input part 41 by theuser (S32), and the internal temperature of the refrigerator is detectedusing the freezing chamber temperature sensor 43 or the refrigeratingchamber temperature sensor 42 (S33).

When the internal temperature of the refrigerator is detected by thesensor, the control part 50 determines whether the internal temperatureof the refrigerator satisfies the desired temperature (S34).

When the internal temperature of the refrigerator satisfies the desiredtemperature, i.e., the temperature of the refrigerating chamber or thefreezing chamber satisfies the desired temperature, the control part 50controls the refrigeration cycle to perform the cold storage operation(low cold energy operation) (S35).

Specifically, the control part 50 controls the evaporator fan 455 to bestopped (S36), and controls the valve device 430 so that the firstoutlet port is opened and the second outlet port is closed (S37).

When the internal temperature of the refrigerator does not satisfy thedesired temperature, the control part 50 controls the refrigerationcycle to perform the high cold air operation, and thus cools an insideof the refrigerator (S38). The case in which the internal temperature ofthe refrigerator does not satisfy the desired temperature is a case inwhich the temperature of the freezing chamber 62 does not satisfy thedesired temperature. When the temperature of the freezing chamber 62satisfies the desired temperature, but the temperature of therefrigerating chamber 63 does not satisfy the desired temperature, therefrigerating chamber damper 69 is controlled to be opened, such thatthe cold air in the refrigeration chamber 81 is introduced into therefrigerating chamber 63.

Specifically, the evaporator fan 455 is controlled to be driven (S39),and the valve device 430 is controlled so that the second outlet port isopened and the first outlet port is closed (S40). Sequentially, theinternal temperature of the refrigerator 3 may be detected, and then itis determined whether to satisfy the desired temperature.

According to the embodiment proposed in the present disclosure, theradiant value of the condenser can be prevented from being lowered dueto the subsidiary condenser, and thus the cooling efficiency of therefrigeration cycle can be increased.

Also, since the phase change material (PCM) is used as the cold storagematerial, the heat exchanging efficiency of the heat exchanger can beenhanced, and the internal temperature of the refrigerator can beconstantly maintained.

Also, since a separate device for increasing the cooling efficiency,except the additional expander, is not provided, an internal design ofthe refrigerator is simple, and the space of the storage chamber can beeffectively used.

Also, since the present disclosure has a simple cycle structure, themanufacturing cost thereof can be reduced.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment. The appearances ofsuch phrases in various places in the specification are not necessarilyall referring to the same embodiment. Further, when a particularfeature, structure, or characteristic is described in connection withany embodiment, it is submitted that it is within the purview of oneskilled in the art to effect such feature, structure, or characteristicin connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A refrigerator comprising: a main body that has astorage chamber; a refrigeration cycle located in the main body andconfigured to supply cold air to the storage chamber, wherein therefrigerant cycle includes: a compressor configured to compress arefrigerant; a condenser configured to condense the refrigerantcompressed by the compressor; a valve device connected to an outlet ofthe condenser; a first branch passage that connects the valve device tothe compressor to flow a portion of the condensed refrigerant dischargedfrom the condenser; a second branch passage that connects the valvedevice to the compressor to flow a remaining portion of the refrigerantdischarged from the condenser; a cold storage expander located at thefirst branch passage and configured to depressurize the portion of thecondensed refrigerant; and a cold storage evaporator located at anoutlet side of the cold storage expander and configured to evaporate thedepressurized refrigerant discharged from the cold storage expander; asubsidiary condenser located at the second branch passage; a condensingexpander located at the second branch passage and between the subsidiarycondenser and the valve device, wherein the subsidiary condenser isconfigured to condense the remaining portion of the refrigerantdepressurized by the condensing expander; an evaporation expanderlocated at an outlet side of the subsidiary condenser and configured todepressurize the remaining portion of the refrigerant condensed by thesubsidiary condenser; a first evaporator configured to evaporate therefrigerant depressurized by the evaporation expander in order to coolthe storage chamber; and a second evaporator located at an outlet sideof the cold storage evaporator and configured to evaporate therefrigerant evaporated by the cold storage evaporator.
 2. Therefrigerator according to claim 1, further comprising a check valvelocated at an inlet side of the first evaporator and configured to guidea one-way flow of the refrigerant toward the compressor.
 3. Therefrigerator according to claim 1, further comprising a cold storagepart that has a phase change material (PCM) therein, wherein thesubsidiary condenser and the cold storage evaporator are located insidethe cold storage part, and wherein the cold storage part exchanges heatwith each of the subsidiary condenser and the cold storage evaporator.4. The refrigerator according to claim 2, wherein the valve device is athree-way valve that has one inlet port, and first and second outletports, wherein the first branch passage is branched from the firstoutlet port, and wherein the second branch passage is branched from thesecond outlet port.
 5. The refrigerator according to claim 4, furthercomprising an input part configured to receive an input of a desiredtemperature of the storage chamber; and a temperature sensor locatedinside the storage chamber, wherein, based on a temperature detected bythe temperature sensor being equal to or higher than the desiredtemperature, the valve device opens the first outlet port and closes thesecond outlet port in order to guide the refrigerant flow toward thecold storage evaporator.
 6. The refrigerator according to claim 5,wherein, based on the temperature detected by the temperature sensorbeing lower than the desired temperature of the storage chamber, thevalve device opens the second outlet port and closes the first outletport in order to guide the refrigerant flow toward the first evaporator.7. The refrigerator according to claim 1, wherein the storage chambercomprises a refrigerating chamber and a freezing chamber, and whereinthe first evaporator is located at a rear wall of the freezing chamber,and the cold storage evaporator and the subsidiary condenser are locatedat a rear wall of the refrigerating chamber.
 8. A control method ofoperating a refrigerator comprising a main body that has a storagechamber, the control method comprising: supplying, by a refrigerationcycle located in the main body, cold air into the storage chamber,wherein the refrigerant cycle includes: a compressor configured tocompress a refrigerant; a condenser configured to condense therefrigerant compressed by the compressor; a valve device connected to anoutlet of the condenser; a first branch passage that connects the valvedevice to the compressor to flow a portion of the condensed refrigerantdischarged from the condenser; a second branch passage that connects thevalve device to the compressor to flow a remaining portion of therefrigerant discharged from the condenser; a cold storage expanderlocated at the first branch passage and configured to depressurize theportion of the condensed refrigerant; and a cold storage evaporatorlocated at an outlet side of the cold storage expander and configured toevaporate the depressurized refrigerant discharged from the cold storageexpander; a subsidiary condenser located at the second branch passage; acondensing expander located at the second branch passage and between thesubsidiary condenser and the valve device, wherein the subsidiarycondenser is configured to condense the remaining portion of therefrigerant depressurized by the condensing expander; an evaporationexpander located at an outlet side of the subsidiary condenser andconfigured to depressurize the remaining portion of the refrigerantcondensed by the subsidiary condenser; a first evaporator configured toevaporate the refrigerant depressurized by the evaporation expander inorder to cool the storage chamber; and a second evaporator located at anoutlet side of the cold storage evaporator and configured to evaporatethe refrigerant evaporated by the cold storage evaporator.
 9. Thecontrol method of claim 8, further comprising guiding, by a check valvelocated at an inlet side of the first evaporator, a one-way flow of therefrigerant toward the compressor.
 10. The control method of claim 8,further comprising exchanging, by a cold storage part that has a phasechange material (PCM) therein, heat with each of the subsidiarycondenser and the cold storage evaporator, wherein the subsidiarycondenser and the cold storage evaporator are located inside the coldstorage part.
 11. The control method of claim 9, further comprising:branching the first branch passage from first outlet port of the valvedevice; and branching the second branch passage from second outlet portof the valve device.
 12. The control method of claim 11, furthercomprising receiving, by an input part of the refrigerator, an input ofdesired temperature of the storage chamber, wherein a temperature sensoris located inside the storage chamber, and wherein, based on atemperature detected by the temperature sensor being equal to or higherthan the desired temperature, the valve device opens the first outletport and closes the second outlet port in order to guide the refrigerantflow toward the cold storage evaporator.
 13. The control method of claim12, further comprising: based on the temperature detected by thetemperature sensor being lower than the desired temperature of thestorage chamber, opening the second outlet port and closing the firstoutlet port, by the valve device, in order to guide the refrigerant flowtoward the first evaporator.